Hot cores in dark clouds

Dec 06, 2011
A false-color, infrared image of a dark cloud as seen against the bright background of Milky Way emission. Within the snake-like cloud structure seen here, dust and gas are congealing into new stars that are detected as embedded, hot cores. New observations with the Submillimeter Array find that these hot cores are often rich in organic chemicals. Credit: NASA/JPL-Caltech

(PhysOrg.com) -- The earliest stages in the life of a star are among the most mysterious. This is primarily because stars form inside dark clouds of material that block optical light, and because they form relatively quickly, in only hundred of thousands of years, whereas once a star starts burning its hydrogen fuel it can last for billions of years.

The details of high birth are the most difficult of all to unravel because massive stars evolve the fastest, and can reach maturity even before their natal birth cloud dissipates. As a result, astronomers infer their presence from hot cores buried deep inside dark clouds, perhaps accompanied by other signposts like outflowing gas or strong .

Infrared dark clouds -- dark patches in the sky seen against the bright infrared galactic background emission -- are rich in molecules and dense gas. They are natural sites for , and the hot cores inside them are thought to be among the earliest stellar embryos. CfA astronomers Steve Longmore and Qizhou Zhang, together with four colleagues, used the Smithsonian's (SMA) to examine two hot cores that were previously discovered in infrared surveys and then confirmed as cores at millimeter wavelengths.

The SMA observations revealed the presence of over a dozen complex molecules including complex nitrogen-, oxygen-, and sulfur-rich species and isotopes of these molecules. The main molecules are CH3CN, CH3OH, CH3OCH3, CH3OCHO, SO, SO2, NH2CHO, C2H5OH, C2H5CN, CN, NH2CHO, H2CS, OCS, and HNCO, although the rich, densely packed spectrum makes some of the identifications uncertain. The SMA provides maps of the hot cores in each of these molecular species. The scientists model the data to conclude that the masses of the two cores are about eight and twenty-six solar-masses, that the temperatures in the material near these young stars are a few hundred kelvin, and that there is evidence for rotating structures (possibly preplanetary disks) around the young stars. The result helps to confirm that these hot cores are massive stars, and the rich chemistry helps trace the details of the stellar birth process in its very early phases.

Explore further: Magnetar discovered close to supernova remnant Kesteven 79

Related Stories

Dark clouds in space

Sep 13, 2011

(PhysOrg.com) -- Infrared dark clouds (IRDCs) are dark patches in the sky seen against the continuous, bright infrared background produced by our galaxy. IRDCs are rich in molecules and relatively dense, cool ...

Studying a Star Before it is Born

Dec 04, 2009

(PhysOrg.com) -- The first phase of a star's formation are thought to begin deep inside a natal cloud of gas and dust. In the earliest stages, material coalesces under the influence of gravity into so-called ...

Turbulence May Promote the Birth of Massive Stars

Feb 23, 2009

(PhysOrg.com) -- On long, dark winter nights, the constellation of Orion the Hunter dominates the sky. Within the Hunter's sword, the Orion Nebula swaddles a cluster of newborn stars called the Trapezium. These stars are ...

Bok Globules

Jun 04, 2010

(PhysOrg.com) -- Bok globules are small interstellar clouds of very cold gas and dust that are so thick they are nearly totally opaque to visible light, although they can be studied with infrared and radio ...

VISTA reveals the secret of the unicorn (w/ Video)

Oct 06, 2010

(PhysOrg.com) -- A new infrared image from ESO’s VISTA survey telescope reveals an extraordinary landscape of glowing tendrils of gas, dark clouds and young stars within the constellation of Monoceros ...

The rich chemistry around an evolved star

Mar 11, 2011

(PhysOrg.com) -- Over 170 molecules have been detected in space, from simple diatomic molecules like CO to complex organic molecules with over 70 atoms, like fullerene.

Recommended for you

How can we find tiny particles in exoplanet atmospheres?

Aug 29, 2014

It may seem like magic, but astronomers have worked out a scheme that will allow them to detect and measure particles ten times smaller than the width of a human hair, even at many light-years distance.  ...

Spitzer telescope witnesses asteroid smashup

Aug 28, 2014

(Phys.org) —NASA's Spitzer Space Telescope has spotted an eruption of dust around a young star, possibly the result of a smashup between large asteroids. This type of collision can eventually lead to the ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

tadchem
not rated yet Dec 06, 2011
It's adiabatic.
Compression >> heating.
Expansion >> cooling.
Pressure is driven by gravity, which is stronger closer to the core.
The ideal gas law is followed until densities approach a significant fraction of the critical density.
Non-ideal gas laws are followed until interactions lead to chemical/nuclear reactions that absorb/emit heat.